I see that fn is not a reserved word. I think that e is just the name given to the event object passed as a parameter. So what is the meaning of e.fn? Is the code assuming that whatever is passed as e has a property called fn? Or is fn some kind of abbreviation that references the function?

网友答案:

Whatever is passed as e should have a property called fn. I would search the rest of the code for "fn" and see what you come up with.